Fluid dispensers of various types are known. In particular, for dispensing of cleaning products such as soaps, there are a wide variety of manually or automatically actuated pumps that dispense a given quantity of the product into a user's hand.
Consumer products may include a dispensing outlet as part of the package, actuated by a user pressing down the top of the package. Such packages use a dip tube extending below the level of the liquid and a piston pump that aspirates the liquid and dispenses it downwards through an outlet spout.
Commercial dispensers frequently use inverted disposable containers that can be placed in dispensing devices, affixed to walls of washrooms or the like. The pump may be integrated as part of the disposable container or may be part of the permanent dispensing device or both. Such devices are generally more robust and, as they are affixed to the wall, greater freedom is available in the direction and amount of force that is required for actuation. Such devices may also use sensors that identify the location of a user's hand and cause a unit dose of the product to be dispensed. This avoids user contact with the device and the associated cross-contamination. It also prevents incorrect operation that can lead to damage and premature ageing of the dispensing mechanism.
A characteristic of inverted dispensers is the need to prevent leakage. Since the pump outlet is located below the container, gravity will act to cause the product to escape if there is any leakage through the pump. This is particularly the case for relatively volatile products such as alcohol based solutions. Achieving leak free operation is often associated with relatively complex and expensive pumps. For the convenience of replacing empty disposable containers however, at least part of the pump is generally also disposable and must be economical to produce. There is therefore a need for a pump that is reliable and drip free, yet simple and economical to produce.
One disposable dispensing system that uses a pump to dispense a unit dose of liquid from an inverted collapsible container has been described in WO2009/104992. The pump is formed of just two elements, namely a resilient pumping chamber and a regulator, having an inner valve and an outer valve. Operation of the pump occurs by application of a lateral force to the pumping chamber, causing it to partially collapse and expel its contents through the outer valve. Refilling of the pumping chamber occurs through the inner valve once the lateral force is removed. The filling force is provided by the inherent resilience of the wall of the pumping chamber, which must be sufficient to overcome any back-pressure due to a resistance to collapse of the container. Although the pump is extremely effective, the lateral force required to operate the pump can sometimes limit its integration into a dispenser body. Other dispensing systems use an axial force i.e. directed in alignment with the direction in which the fluid is dispensed. It would be desirable to provide a pump that could operate in this manner that could also be integrated into existing axially operating dispensers.